Bite the bullet and replace the tank, sender and while you're at it the lines also. Except for spending the money you'll have no regrets. toolman PS. I got my tank @ gastanks.com (Quanta Products)
I agree with ToolManMike, just buy a new tank and sending unit. I had a small hole in mine and did an epoxy patch. It lasted a year. When the patch fell off there was a much bigger hole.
It sucks spending money but the peace of mind you get with installin new parts is unmesureable. ALso try Rockauto.com for a tank.